1. Field of the Invention
The present invention relates to a transmission network system.
2. Description of the Related Art
As a method of authenticating a time when certain data is generated or processed, there is a time authentication method through a transmission network. As a conventional general time authentication method, there is a method in which a user device transmits an authentication request and authentication object data to an authentication server connected through a transmission network as an authentication request process in the user device (such as a computer). The conventional time authentication method is a method in which the authentication server authenticates a time when the authentication server receives the authentication object data as an authentication time.
Although the authentication time that is authenticated as a time when data is generated or processed should be in nature a time when a user performs the authentication request process, the authentication time in the conventional time authentication method is a reception time by the authentication server. There is a difference between the time when the authentication request process is performed and the reception time of the authentication server. The difference between the times is a delay time from several milliseconds to several seconds depending mainly on a transmission distance in the network between the user device and the authentication server and the number of passed nodes. The delay time is different for each user device.
When the intended use of the time authentication is a conventional main use of the time authentication such as a use for authenticating a time when a patent document or an accounting document is generated or processed, it cannot necessarily be said that the difference between the time when the authentication request process is performed and the reception time of the authentication server is a problem. However, in services varying in recent years as the number of users increases and the speed of transmission networks increases, in particular, in electronic commerce and the like, when authenticating a time when a user performs a transaction request or performing transaction sequence management based on the time, the difference between the times is a problem.
Specifically, in the electronic commerce and the like, a delay time between the user device and the authentication server due to the transmission network is a cause of inequality that directly affects a large pecuniary profit or loss of the user, so that the delay time becomes a problem. Therefore, the delay time between the user device and the authentication server is a problem to be solved for a service provider to guarantee impartial provision of services to users.
As the time authentication method, a method is considered in which the user device adds the authentication time to the authentication object data and the authentication server performs the time authentication on the basis of the authentication time added to the authentication object data. However, this method has a problem of accuracy and credibility of the time because the method uses the time managed by the user device.
Conventionally, a technique for solving the problem due to the delay time between the user device and the authentication server in these time authentication methods is proposed (for example, see JP-2002-366031-A). In the JP-2002-366031-A, a problem is described as follows: “An object of the present invention is to provide a technique to issue and authenticate a high-accuracy and high-reliability authentication time which is a processing time of processing information of a computer”. A means for solving the problem is described as follows: “A configuration is employed in which accuracy of a clock is improved by synchronizing the clock with a reliable time acquired from a network, the clock is designed to be not able to be operated from inside, and the clock is designed to be able to be operated from outside by only a determined procedure, and a configuration is employed in which when authentication time issuance is requested, the authentication time for the authentication time issuance request is issued by using a time generated by the clock. Thereby, a high-accuracy authentication time without falsification can be issued. Then a configuration is employed in which an encrypted authentication time recorded in processing information in this way is decoded and the decoded authentication time is authenticated as the processing time of the processing information. Thereby, it is possible to authenticate the processing time of the processing information to be authenticated with high accuracy and high reliability”.
On the other hand, as techniques for synchronizing times of devices in a transmission network, NTP (Network Time Protocol), IEEE 1588v2/PTP (Precision Time Protocol), or the like are known (see, IEEE 1588-2008). Any of these techniques defines a time synchronization method between a server that provides a stable time and a client that follows the time of the server. Although the accuracy of the time synchronization depends on an implementation method of the device, it is said that the accuracy is millisecond order in the NTP and microsecond order in the IEEE 1588v2/PTP.